I finally found a "fall project". I was looking for something fun to
do in the fall, fixing some item or another. Last year I did a diesel
engine Cummins L423D.

I just won this in a liquidation auction:

http://igor.chudov.com/tmp/Quincy-QT-10-Compressor/

I want to add a VFD to this compressor and sell it with a VFD to
someone who has single phase only.

I need to find a drive now, but I hope that I can do so for a
reasonable price.

i

Ignoramus27577 wrote:
I finally found a "fall project". I was looking for something fun to
do in the fall, fixing some item or another. Last year I did a diesel
engine Cummins L423D.

I just won this in a liquidation auction:

http://igor.chudov.com/tmp/Quincy-QT-10-Compressor/

I want to add a VFD to this compressor and sell it with a VFD to
someone who has single phase only.

I need to find a drive now, but I hope that I can do so for a
reasonable price.

i

Whoo-hoo! That looks to be a pretty good find! Want to trade?

Just kidding. I need at least a 15 hp motor to stand a chance of getting
3-phase installed at my place.

Btw, the local Quincy service rep has been great for supplying .pdf files
of all the manuals for my model.

Todd

On 2007-10-17, Todd Rich wrote:
Ignoramus27577 wrote:
I finally found a "fall project". I was looking for something fun to
do in the fall, fixing some item or another. Last year I did a diesel
engine Cummins L423D.

I just won this in a liquidation auction:

http://igor.chudov.com/tmp/Quincy-QT-10-Compressor/

I want to add a VFD to this compressor and sell it with a VFD to
someone who has single phase only.

I need to find a drive now, but I hope that I can do so for a
reasonable price.

i

Whoo-hoo! That looks to be a pretty good find! Want to trade?

This one, is about as big as I can handle!!!

Just kidding. I need at least a 15 hp motor to stand a chance of getting
3-phase installed at my place.

And 10 HP is about as much as I can run at home, even with a drive (60
amp subpanel).

Btw, the local Quincy service rep has been great for supplying .pdf files
of all the manuals for my model.


I just uploaded a brochure on my website (not a manual).

It does about 35 CFM, if I recall correctly.

i

Todd, thanks for a suggestion to ask them for a manual.

http://igor.chudov.com/tmp/Quincy-QT-10-Compressor/

Quincy just emailed me the manual and I uploaded it there and to my
downloadable manuals archive.

i

Hmmm ... single stage! In my limited experience, the large compressors
have been 2 stage. Now that I think about it, 2 stage gives you higher
pressure, but single stage greater cfm (for same horsepower). I think.

Bob

On 2007-10-17, Bob Engelhardt wrote:
Hmmm ... single stage! In my limited experience, the large compressors
have been 2 stage. Now that I think about it, 2 stage gives you higher
pressure, but single stage greater cfm (for same horsepower). I think.


I am not sure, yet, if it is single stage or not. I am going to have a
look in a couple of days.

i

You can see the second-stage cylinders behind the larger first-stage
cylinders in the photos.

"Ignoramus27577" wrote in message
...
On 2007-10-17, Bob Engelhardt wrote:
Hmmm ... single stage! In my limited experience, the large compressors
have been 2 stage. Now that I think about it, 2 stage gives you higher
pressure, but single stage greater cfm (for same horsepower). I think.


I am not sure, yet, if it is single stage or not. I am going to have a
look in a couple of days.

i

Bob Engelhardt wrote:
Hmmm ... single stage! In my limited experience, the large compressors
have been 2 stage. Now that I think about it, 2 stage gives you higher
pressure, but single stage greater cfm (for same horsepower). I think.

Bob

Why do you think it is a single stage compressor? It looks like from the
literature, all the QT models are 2-stage compressors.

Lasting Performance
Available in a full range of horsepower
increments, the Quincy QT two-stage
compressor has been built exclusively
for industrial, automotive, and
commercial applications requiring up
to 175 psig. Heavy duty, cast iron
construction ensures durability . even
in the most demanding environments.

On Wed, 17 Oct 2007 11:34:52 -0500, Ignoramus27577
wrote:

On 2007-10-17, Bob Engelhardt wrote:
Hmmm ... single stage! In my limited experience, the large compressors
have been 2 stage. Now that I think about it, 2 stage gives you higher
pressure, but single stage greater cfm (for same horsepower). I think.


I am not sure, yet, if it is single stage or not. I am going to have a
look in a couple of days.

i


Hey nIggy,

It has two intakes with filters. It is a 2 cylinder single stage. A
2-stage has only a single inlet. The output from that first stage
goes to the second stage cylinder, which also will be smaller.

Bob Engelhardt wrote:
Hmmm ... single stage! In my limited experience, the large compressors
have been 2 stage. Now that I think about it, 2 stage gives you higher
pressure, but single stage greater cfm (for same horsepower). I think.
No, absolutely not. A 2 Hp single-stage compressor delivers
about 6.4 CFM at 90 PSI. A 2 Hp two-stage compressor will
deliver 9 - 12 CFM at 175 PSI or so. Even after regulating down
to 90 PSI, it at least 50 % more air volume. This seems totally
counter-intuitive as regulating down from 175 to 90 PSI is
throwing away about half the energy.

Jon

Brian Lawson wrote:
On Wed, 17 Oct 2007 11:34:52 -0500, Ignoramus27577
wrote:

On 2007-10-17, Bob Engelhardt wrote:
Hmmm ... single stage! In my limited experience, the large compressors
have been 2 stage. Now that I think about it, 2 stage gives you higher
pressure, but single stage greater cfm (for same horsepower). I think.

I am not sure, yet, if it is single stage or not. I am going to have a
look in a couple of days.

i


Hey nIggy,

It has two intakes with filters. It is a 2 cylinder single stage. A
2-stage has only a single inlet. The output from that first stage
goes to the second stage cylinder, which also will be smaller.

Brian,

It is a four cylinder, two stage. Each bank has a low pressure and a
high pressure cylinder. Admittedly I haven ever seen that particular
configuration but the documentations shows that. It is in fact a QT-15,
not a QT-10 as it says on the tank.

The high pressure cylinder is just barely visible beyond the low
pressure, look low, just above the crankcase and you can see the high
pressure cylinder.

George

Ignoramus27577 wrote:

I just won this in a liquidation auction:

http://igor.chudov.com/tmp/Quincy-QT-10-Compressor/

I want to add a VFD to this compressor and sell it with a VFD to
someone who has single phase only.

I need to find a drive now, but I hope that I can do so for a
reasonable price.
NICE compressor. Quincy's are really top of the line. You need
to arrange the VFD to get it up to speed before the unloaders
kick out. There may be some way to control the time delay,
although this one doesn't look like it has electrical controls
for the unloader.

I got a smaller, single-stage Quincy at a scrap yard that had a
continuous-run motor and totally pneumatic pressure controls
(using the unloaders). I built a microcontroller-based
dual-mode controller for it that unloads for spin up, waits for
oil pressure to build, then loads the compressor, and keeps the
motor on for one minute after no more air is needed. The
unloader is controlled with a solenoid air valve. The motor is
controlled with a 50 A, 400 V solid state relay. See pix at
http://jelinux.pico-systems.com/aircomp.html
The box above the motor is the controller. The white thing to
the right of the tank is a refrigerated air dryer that I hauled
out of the trash at work.

With 2 HP, the sensible thing was to go with a single-phase
motor. You'd need to derate the VFD for the compressor
application, but it ought to work. The slow start of the 10 Hp
motor/flywheel should be much nicer to the neighborhood, too.

Jon

On 2007-10-17, David Courtney wrote:
You can see the second-stage cylinders behind the larger first-stage

Yes, that's right, that was why I suspected that it was 2 stage.

Thanks. I will see.

i


"Ignoramus27577" wrote in message
...
On 2007-10-17, Bob Engelhardt wrote:
Hmmm ... single stage! In my limited experience, the large compressors
have been 2 stage. Now that I think about it, 2 stage gives you higher
pressure, but single stage greater cfm (for same horsepower). I think.


I am not sure, yet, if it is single stage or not. I am going to have a
look in a couple of days.

i

On 2007-10-17, George wrote:
Brian Lawson wrote:
On Wed, 17 Oct 2007 11:34:52 -0500, Ignoramus27577
wrote:

On 2007-10-17, Bob Engelhardt wrote:
Hmmm ... single stage! In my limited experience, the large compressors
have been 2 stage. Now that I think about it, 2 stage gives you higher
pressure, but single stage greater cfm (for same horsepower). I think.

I am not sure, yet, if it is single stage or not. I am going to have a
look in a couple of days.

i


Hey nIggy,

It has two intakes with filters. It is a 2 cylinder single stage. A
2-stage has only a single inlet. The output from that first stage
goes to the second stage cylinder, which also will be smaller.

Brian,

It is a four cylinder, two stage. Each bank has a low pressure and a
high pressure cylinder. Admittedly I haven ever seen that particular
configuration but the documentations shows that. It is in fact a QT-15,
not a QT-10 as it says on the tank.

The high pressure cylinder is just barely visible beyond the low
pressure, look low, just above the crankcase and you can see the high
pressure cylinder.

George

Surprisingly, in agreement with what you just said about QT-15, the
Quincy service rep emailed me the manual for QT-15. I thought that he
simply made a mistake. But he told me, once I said there is two
cylinders on each side of the V, that "I know exactly what pump you
have". And he sent me the QT-15 manual. Now I see this in a different
lightl. It looks like a QT-15 with a 10 HP motor.

i

On 2007-10-17, Jon Elson wrote:
Bob Engelhardt wrote:
Hmmm ... single stage! In my limited experience, the large compressors
have been 2 stage. Now that I think about it, 2 stage gives you higher
pressure, but single stage greater cfm (for same horsepower). I think.
No, absolutely not. A 2 Hp single-stage compressor delivers
about 6.4 CFM at 90 PSI. A 2 Hp two-stage compressor will
deliver 9 - 12 CFM at 175 PSI or so. Even after regulating down
to 90 PSI, it at least 50 % more air volume. This seems totally
counter-intuitive as regulating down from 175 to 90 PSI is
throwing away about half the energy.

Jon

The reason for it is that compression is no longer adiabatic, the air
is cooled between stages, right? So less energy is lost as heat?

How come there are no three stage compressors?

i

Todd Rich wrote:
Why do you think it is a single stage compressor? It looks like
from the
literature, all the QT models are 2-stage compressors.

From the pictures. It looks like 2 cylinders, each with an air intake.
The 2nd stage cylinders are behind & not easily visible. Bob

Ignoramus27577 wrote:

On 2007-10-17, Jon Elson wrote:
Bob Engelhardt wrote:
Hmmm ... single stage! In my limited experience, the large compressors
have been 2 stage. Now that I think about it, 2 stage gives you higher
pressure, but single stage greater cfm (for same horsepower). I think.
No, absolutely not. A 2 Hp single-stage compressor delivers
about 6.4 CFM at 90 PSI. A 2 Hp two-stage compressor will
deliver 9 - 12 CFM at 175 PSI or so. Even after regulating down
to 90 PSI, it at least 50 % more air volume. This seems totally
counter-intuitive as regulating down from 175 to 90 PSI is
throwing away about half the energy.

Jon

The reason for it is that compression is no longer adiabatic, the air
is cooled between stages, right? So less energy is lost as heat?

How come there are no three stage compressors?

There most certainly are three (and more) stage compressors. They are
common for such things as filling SCUBA / SCBA tanks, and also used at
the various industrial gas suppliers to fill the various high pressure
gas cylinders.

In article ,
Ignoramus27577 wrote:
How come there are no three stage compressors?

I personally used to work near a 4-stage - but it was not used much.
Several thousand PSI out, as best I recall. Fed into a wind tunnel...

There's one 3-stage on that watery inlet auction site as I write. Again,
high-pressure, special application.

"Bauer Mariner 3 Stage Air Compressor"

--
Cats, coffee, chocolate...vices to live by

In article ,
Ignoramus27577 wrote:
Surprisingly, in agreement with what you just said about QT-15, the
Quincy service rep emailed me the manual for QT-15. I thought that he
simply made a mistake. But he told me, once I said there is two
cylinders on each side of the V, that "I know exactly what pump you
have". And he sent me the QT-15 manual. Now I see this in a different
lightl. It looks like a QT-15 with a 10 HP motor.

Which would be an excellent setup for longevity if the pulleys are set
up right. Running a larger pump slower increases its lifespan, not that
Quincy's wear out particularly fast in the first place.

--
Cats, coffee, chocolate...vices to live by

On 2007-10-17, Jon Elson wrote:
Ignoramus27577 wrote:

I just won this in a liquidation auction:

http://igor.chudov.com/tmp/Quincy-QT-10-Compressor/

I want to add a VFD to this compressor and sell it with a VFD to
someone who has single phase only.

I need to find a drive now, but I hope that I can do so for a
reasonable price.
NICE compressor. Quincy's are really top of the line. You need
to arrange the VFD to get it up to speed before the unloaders
kick out. There may be some way to control the time delay,
although this one doesn't look like it has electrical controls
for the unloader.

There should, though, be an unloader valve somewhere, right?

There are some little copper lines on the top of the head?

I got a smaller, single-stage Quincy at a scrap yard that had a

That's awesome.

continuous-run motor and totally pneumatic pressure controls
(using the unloaders). I built a microcontroller-based
dual-mode controller for it that unloads for spin up, waits for
oil pressure to build, then loads the compressor, and keeps the
motor on for one minute after no more air is needed. The
unloader is controlled with a solenoid air valve. The motor is
controlled with a 50 A, 400 V solid state relay. See pix at
http://jelinux.pico-systems.com/aircomp.html

Very cute.

The box above the motor is the controller. The white thing to
the right of the tank is a refrigerated air dryer that I hauled
out of the trash at work.

I have a dryer, too. (also got it from trash, but had to pay $10) I
use dry air for almost everything, these days.

With 2 HP, the sensible thing was to go with a single-phase
motor. You'd need to derate the VFD for the compressor
application, but it ought to work. The slow start of the 10 Hp
motor/flywheel should be much nicer to the neighborhood, too.

I am thinking about maybe 0.5 sec acceleration. 1 second at most.

i

On 2007-10-17, Ecnerwal wrote:
In article ,
Ignoramus27577 wrote:
Surprisingly, in agreement with what you just said about QT-15, the
Quincy service rep emailed me the manual for QT-15. I thought that he
simply made a mistake. But he told me, once I said there is two
cylinders on each side of the V, that "I know exactly what pump you
have". And he sent me the QT-15 manual. Now I see this in a different
lightl. It looks like a QT-15 with a 10 HP motor.

Which would be an excellent setup for longevity if the pulleys are set
up right. Running a larger pump slower increases its lifespan, not that
Quincy's wear out particularly fast in the first place.


Yes, being in the middle between min and max RPM, indeed is great for
a lot of reasons.

i

On Wed, 17 Oct 2007 17:15:51 GMT, George wrote:

Brian Lawson wrote:
On Wed, 17 Oct 2007 11:34:52 -0500, Ignoramus27577
wrote:

On 2007-10-17, Bob Engelhardt wrote:
Hmmm ... single stage! In my limited experience, the large compressors
have been 2 stage. Now that I think about it, 2 stage gives you higher
pressure, but single stage greater cfm (for same horsepower). I think.

I am not sure, yet, if it is single stage or not. I am going to have a
look in a couple of days.

i


Hey nIggy,

It has two intakes with filters. It is a 2 cylinder single stage. A
2-stage has only a single inlet. The output from that first stage
goes to the second stage cylinder, which also will be smaller.

Brian,

It is a four cylinder, two stage. Each bank has a low pressure and a
high pressure cylinder. Admittedly I haven ever seen that particular
configuration but the documentations shows that. It is in fact a QT-15,
not a QT-10 as it says on the tank.

The high pressure cylinder is just barely visible beyond the low
pressure, look low, just above the crankcase and you can see the high
pressure cylinder.

George


Hey George,

Sorry, but I didn't look that close. I stand corrected.

And Wow!! That sucker will produce some air!!

Take care.

Brian.

Ignoramus27577 wrote:


There should, though, be an unloader valve somewhere, right?
I think the unloaders are those brass pieces sticking out of the
cylinder heads. (Those look different than mine.)
What controls the unloader can vary. On compressors with motor
controls, they often use a valve that is operated by oil pressure.
When the oil pressure is developed, the valve shuts off air and the
unloaders allow the compressor intake valves to work.


There are some little copper lines on the top of the head?
Yes, mine are operated by a diaphragm about 1.5" diameter. Maybe due to
the higher pressure of the 2-stage, the unloaders are smaller.
Yes, some copper lines apply air to the unloaders to lock the intake
valves open.

Jon

Brian Lawson wrote:
On Wed, 17 Oct 2007 17:15:51 GMT, George wrote:

Brian Lawson wrote:
On Wed, 17 Oct 2007 11:34:52 -0500, Ignoramus27577
wrote:

On 2007-10-17, Bob Engelhardt wrote:
Hmmm ... single stage! In my limited experience, the large compressors
have been 2 stage. Now that I think about it, 2 stage gives you higher
pressure, but single stage greater cfm (for same horsepower). I think.

I am not sure, yet, if it is single stage or not. I am going to have a
look in a couple of days.

i

Hey nIggy,

It has two intakes with filters. It is a 2 cylinder single stage. A
2-stage has only a single inlet. The output from that first stage
goes to the second stage cylinder, which also will be smaller.
Brian,

It is a four cylinder, two stage. Each bank has a low pressure and a
high pressure cylinder. Admittedly I haven ever seen that particular
configuration but the documentations shows that. It is in fact a QT-15,
not a QT-10 as it says on the tank.

The high pressure cylinder is just barely visible beyond the low
pressure, look low, just above the crankcase and you can see the high
pressure cylinder.

George


Hey George,

Sorry, but I didn't look that close. I stand corrected.

And Wow!! That sucker will produce some air!!

Take care.

Brian.

Yes indeedy, only thing I have seen that will produce more air is a
Southern Democrat, passionately defending his beliefs.

George

On Oct 17, 5:07 pm, Jon Elson wrote:
Bob Engelhardt wrote:
Hmmm ... single stage! In my limited experience, the large compressors
have been 2 stage. Now that I think about it, 2 stage gives you higher
pressure, but single stage greater cfm (for same horsepower). I think.

No, absolutely not. A 2 Hp single-stage compressor delivers
about 6.4 CFM at 90 PSI. A 2 Hp two-stage compressor will
deliver 9 - 12 CFM at 175 PSI or so. Even after regulating down
to 90 PSI, it at least 50 % more air volume. This seems totally
counter-intuitive as regulating down from 175 to 90 PSI is
throwing away about half the energy.

I'm not entirely convinced by this. Suppose two compressors supply air
at the same rate (the same CFM, measured at atmospheric pressure). One
supplies the air at 90 PSI and the other at 175 PSI. There is more
energy stored in the air supplied at 175 PSI, which means that a
larger motor will be required to drive the compressor. So if instead
you start with a pair of 2 hp motors and use them to drive compressors
supplying air at 90 PSI and 175 PSI, the compressor supplying air at
90 PSI ought to be able to supply air at a greater rate.

Best wishes,

Chris

On Oct 17, 2:53 pm, Ignoramus27577 ignoramus27...@NOSPAM.
27577.invalid wrote:
I finally found a "fall project". I was looking for something fun to
do in the fall, fixing some item or another. Last year I did a diesel
engine Cummins L423D.

I just won this in a liquidation auction:

http://igor.chudov.com/tmp/Quincy-QT-10-Compressor/

I want to add a VFD to this compressor and sell it with a VFD to
someone who has single phase only.

I need to find a drive now, but I hope that I can do so for a
reasonable price.

i

Just out of curiousity (if you don't mind saying), what are you paying
for the compressor?

Best wishes,

Chris

On Oct 17, 5:07 pm, Jon Elson wrote:
Bob Engelhardt wrote:
Hmmm ... single stage! In my limited experience, the large compressors
have been 2 stage. Now that I think about it, 2 stage gives you higher
pressure, but single stage greater cfm (for same horsepower). I think.

No, absolutely not. A 2 Hp single-stage compressor delivers
about 6.4 CFM at 90 PSI. A 2 Hp two-stage compressor will
deliver 9 - 12 CFM at 175 PSI or so. Even after regulating down
to 90 PSI, it at least 50 % more air volume. This seems totally
counter-intuitive as regulating down from 175 to 90 PSI is
throwing away about half the energy.

I'm not entirely convinced by this. Suppose two compressors supply air
at the same rate (the same CFM, measured at atmospheric pressure). One
supplies the air at 90 PSI and the other at 175 PSI. There is more
energy stored in the air supplied at 175 PSI, which means that a
larger motor will be required to drive the compressor. So if instead
you start with a pair of 2 hp motors and use them to drive compressors
supplying air at 90 PSI and 175 PSI, the compressor supplying air at
90 PSI ought to be able to supply air at a greater rate.

Best wishes,

Chris

On 2007-10-18, Christopher Tidy wrote:
On Oct 17, 2:53 pm, Ignoramus27577 ignoramus27...@NOSPAM.
27577.invalid wrote:
I finally found a "fall project". I was looking for something fun to
do in the fall, fixing some item or another. Last year I did a diesel
engine Cummins L423D.

I just won this in a liquidation auction:

http://igor.chudov.com/tmp/Quincy-QT-10-Compressor/

I want to add a VFD to this compressor and sell it with a VFD to
someone who has single phase only.

I need to find a drive now, but I hope that I can do so for a
reasonable price.

i

Just out of curiousity (if you don't mind saying), what are you paying
for the compressor?

My bid was $375, but with the buyer's fee, the total was $423.

i

Found a drive for it, a 18.5 kW Siemens SED2 drive (240v, 25 HP). I
will report how it works out. I am mindful of the possibility that
this whole system is 15 HP and not 10, as claimed. I will pick up
around Tuesday.

i

Christopher Tidy wrote:
On Oct 17, 5:07 pm, Jon Elson wrote:

Bob Engelhardt wrote:

Hmmm ... single stage! In my limited experience, the large compressors
have been 2 stage. Now that I think about it, 2 stage gives you higher
pressure, but single stage greater cfm (for same horsepower). I think.

No, absolutely not. A 2 Hp single-stage compressor delivers
about 6.4 CFM at 90 PSI. A 2 Hp two-stage compressor will
deliver 9 - 12 CFM at 175 PSI or so. Even after regulating down
to 90 PSI, it at least 50 % more air volume. This seems totally
counter-intuitive as regulating down from 175 to 90 PSI is
throwing away about half the energy.


I'm not entirely convinced by this. Suppose two compressors supply air
at the same rate (the same CFM, measured at atmospheric pressure). One
supplies the air at 90 PSI and the other at 175 PSI. There is more
energy stored in the air supplied at 175 PSI, which means that a
larger motor will be required to drive the compressor.

Yes, in the absence of any empirical data, what you say makes perfect
sense. But, go look at the rating sheets for some industrial
compressors (watch out for those "Sears" ratings with the 5+ Hp motors
that run on a standard 120 V outlet) and you will see that the 2-stage
compressors have a LOT more air delivery than a single stage, for the
same HP.

So if instead
you start with a pair of 2 hp motors and use them to drive compressors
supplying air at 90 PSI and 175 PSI, the compressor supplying air at
90 PSI ought to be able to supply air at a greater rate.
Maybe Iggy hit on the reason, the single stage HAS to be adiabatic,
the 2-stage has an intercooler that cools the air before the 2nd stage.
Now, that heat is lost, but it allows the 2nd stage to draw in cooler
air. Well, I'm not a thermodynamics expert. But, I have seen this
effect on so MANY rating sheets for compressors, some basic physics has
to be responsible for it.

There is an unavoidable loss in any compressor, having to do with the
volume of air left in the cylinder when the piston reaches TDC. You
exerted work to compress it, and when the valve shuts and the piston
heads back down, you get very little of that work back. If you do all
the compressing in a single stage, your only aid is to minimize this
dead volume. With a 2-stage, doing the compression in a series of
cylinders must greatly reduce the loss associated with the dead volume.

Jon

On 17 Oct 2007 23:41:17 -0700, Christopher Tidy
wrote:

On Oct 17, 5:07 pm, Jon Elson wrote:
Bob Engelhardt wrote:
Hmmm ... single stage! In my limited experience, the large compressors
have been 2 stage. Now that I think about it, 2 stage gives you higher
pressure, but single stage greater cfm (for same horsepower). I think.

No, absolutely not. A 2 Hp single-stage compressor delivers
about 6.4 CFM at 90 PSI. A 2 Hp two-stage compressor will
deliver 9 - 12 CFM at 175 PSI or so. Even after regulating down
to 90 PSI, it at least 50 % more air volume. This seems totally
counter-intuitive as regulating down from 175 to 90 PSI is
throwing away about half the energy.

I'm not entirely convinced by this. Suppose two compressors supply air
at the same rate (the same CFM, measured at atmospheric pressure). One
supplies the air at 90 PSI and the other at 175 PSI. There is more
energy stored in the air supplied at 175 PSI, which means that a
larger motor will be required to drive the compressor. So if instead
you start with a pair of 2 hp motors and use them to drive compressors
supplying air at 90 PSI and 175 PSI, the compressor supplying air at
90 PSI ought to be able to supply air at a greater rate.

Best wishes,

Chris


How big is the tank? Say you have a 5CF tank and a 5cfm compressor at
90 PSI.
You also have a 2.5 cf tank and a 2.5cfm at 180psi compressor.

Both take roughly 2HP. Both pump the same amount of air but one store
it at twice the pressure. With a regulator set to less than 90 PSI
both provide the same amount of air.

Theoretically.

In real life the 180psi compressor would likely take a bit more power
because of the higher pressure - but not a significant amount.

--
Posted via a free Usenet account from http://www.teranews.com

On Oct 18, 11:33 am, Ignoramus1624
wrote:
On 2007-10-18, Christopher Tidy wrote:



On Oct 17, 2:53 pm, Ignoramus27577 ignoramus27...@NOSPAM.
27577.invalid wrote:
I finally found a "fall project". I was looking for something fun to
do in the fall, fixing some item or another. Last year I did a diesel
engine Cummins L423D.

I just won this in a liquidation auction:

http://igor.chudov.com/tmp/Quincy-QT-10-Compressor/

I want to add a VFD to this compressor and sell it with a VFD to
someone who has single phase only.

I need to find a drive now, but I hope that I can do so for a
reasonable price.

i

Just out of curiousity (if you don't mind saying), what are you paying
for the compressor?

My bid was $375, but with the buyer's fee, the total was $423.

i

Sounds like a good deal!

Chris